The field of microfluidics is undergoing rapid growth in terms of new device and system development.Among the many methods of fabricating microfluidic devices and systems, surface micromachining is relatively underrepresented due tw difficulties in the introduction of fluids into the very small channels produced, packaging problems, and difficulties in device and system characterization. The potential advantages of using surface micromachining includti compatibility with the existing integrated circuit tool set, integration of electronic sensing and actuation with microfluidics, and fluid volume minimization. In order to explore these potential advantages we have developed first generation surface micromachined microfluidic devices (channels) using an adapted pressure sensor fabrication procms to produce silicon nitride channels, and the SUMMiT process to produce polysilicon channels. The channels were characterized by leak testing and flow rate vs. pressure measurements. The fabrication processes used and results of these tests are reported in this paper.

Ion-assisted pulsed laser deposition has been used to produce films containing ≳85% sp3-bonded cubic boron nitride (c-BN). By ablating from a target of hexagonal boron nitride (h-BN), BN films have been deposited on heated (50–800 °C) Si(100) surfaces. The growing films are irradiated with ions from a broad beam ion source operated with Ar and N2 source gasses. Successful c-BN synthesis has been confirmed by Fourier transform infrared (FTIR) spectroscopy, high-resolution transmission electron microscopy (TEM), selected-area electron diffraction, electron energy-loss spectroscopy, and x-ray diffraction. The films are polycrystalline and show grain sizes up to 300 Å. In addition, Rutherford backscattering, elastic recoil detection, and Auger electron spectroscopies have been used to further characterize the samples. The effects of varying ion current density, substrate growth temperature, growth time, and ion energy have been investigated. It is found that stoichiometric films with a high c-BN percentage can be grown between 150 and 500 °C. Below ∼150 °C, the c-BN percentage drops dramatically, and the deposited film is completely resputtered at the current densities and ablation deposition rates used. As the deposition temperature rises above ∼500 °C the c-BN percentage also drops, but less dramatically than at low temperatures. In addition, the IR-active c-BN mode narrows considerably as the deposition temperature increases, suggesting that the c-BN material has fewer defects or larger grain size. It is found that films with a high c-BN percentage are deposited only in a narrow window of ion/atom arrival values that are near unity at beam energies between 800 and 1200 eV. Below this window the deposited films have a low c-BN percentage, and above this window the deposited film is completely resputtered. Using FTIR analysis, it is found that the c-BN percentage in these samples is dependent upon growth time. The initial deposit is essentially all sp2-bonded material and sp3-bonded material forms above this layer. Consistently, cross-section TEM samples reveal this layer to consist of an amorphous BN layer (∼30 Å thick) directly on the Si substrate followed by highly oriented turbostratic BN (∼300 Å thick) and finally the c-BN layer. The h-BN/t-BN interfacial layer is oriented with the 002 basal planes perpendicular to the plane of the substrate. Importantly, the position of the c-BN IR phonon changes with growth time. Initially this mode appears near 1130 cm−1 and decreases with growth time to a constant value of 1085 cm−1. Since in bulk c-BN the IR mode appears at 1065 cm−1, a large compressive stress induced by the ion bombardment is suggested. Possible mechanisms are commented on for the conversion process to c-BN based upon the results.

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The electronic spectra of Re(CO)sX (X = Cl, Br, I), [M(CO)5NH2CH3]Cl (M = Mn, Re), and [(C2Hs)4N] [M(CO)sBr] (M = Cr, W) have been measured. The emission spectra and photochemistry of the Re(CO)sX complexes have also been investigated. The new electronic spectral studies along with data in the literature allow definitive assignment of the lowest absorptions as ligand field (LF) 1Ai (e4b22) -*• 1 -3E(e3b22ai1) for a large class of low-spin d6 M(CO)sX complexes. Emission from Re(CO)sX occurs from the 3E(e3b22ai') state and is strongly dependent on temperature in the range 20-100 K. Quantitative emission measurements have been made for the pure solids. Photochemistry of Re(CO)sX at 298 K involves substitution of CO with a quantum yield of up to 0.76 depending on X and the excitation wavelength. The observed chemistry and variable quantum yields accord well with the electronic nature of the lowest excited states.